Ravn Air Group on 30 December says it expects schedule disruptions through January as its Alaska-based regional airline recovers from an attack on the company’s networks that forced it to cancel flights of its De Havilland Canada Dash 8-100s.

The Alaska-based company is coordinating with the US Federal Bureau of Investigation, government agencies and private sector cybersecurity consultants following the attack on its networks on 20 December. Its three airlines RavnAir Alaska, PenAir and RavnAirConnect are still flying passengers on its routes throughout Alaska.

When the company announced the attack on 21 December it cancelled all flights on RavnAir Alaska’s De Havilland Canada Dash 8-100s through noon local time, since the attack forced them to disconnect both its maintenance network and the backup network for those aircraft.

Besides those 10 DHC-8-100s in service, RavnAir Alaska’s fleet includes a Cessna 208 Caravan turboprop and two Bombardier Short 330-200s, according to Cirium’s fleet data. As of 23 December, the airline stated that 14% of RavnAir Alaska’s flights had been impacted by the attack, as the Dash 8 maintenance network was still being restored.

Ravn and the FBI did not give details about the attack but the company states on 30 December that “the impact of this disruption now appears more extensive than initially reported”.

“It may take as long as one month to have all affected IT systems fully restored and back to normal,” Ravn states. “Given this news, customers should expect some additional cancellations and delays at all three airlines as recovery efforts continue in coordination with government officials and outside cyber crime experts.”